StageOneRequirements
We start where the business outcome is, not where the backlog is. What has to be true for this application to be worth running, which users notice when it is not, and what the current release actually costs to ship.
Most estates arrive with a backlog nobody has pruned in two years. Deciding what not to build is the first saving.
A scoped backlog and a baseline
Requirements traced to a business outcome, with the current release cadence, defect rate and environment inventory recorded as they stand today.
This is yours whether or not the engagement continues.